Silver halide emulsions



United States Patent SILVER HALIDE EMULSIONS Frederick Charles Forsgard, New Brunswick, N.J., as-

signor to E. I. (in Pout de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Application September 30, 1957 Serial No. 686,869

8 Claims. 31. 96-87) This invention relates to radiation-sensitive silver halide emulsions of increased sensitivity. More particularly, it relates to such emulsions which contain as the sensitizing agent a condensation product of an N-alkylaniline with ethylene oxide which product contains at least three -CH CH O- groups. Still more particularly, it relates to photographic gelatino silver halide emulsions sensitized with such agents. The invention also relates to photographic elements bearing a layer of such emulsions.

It is known to increase the radiation response and contrast of silver halide emulsions by the addition of non-optical sensitizers. Useful such sensitizers are the polyalkylene glycols and their derivatives which are described in US. patents to Blake, Nos. 2,400,532, 2,423,549, and 2,441,389. However, these compounds tend to cause slight fog in emulsions to which they are added, particularly when photographic materials coated with said emulsions are stored for'any length of time.

2 or more. Thus, X is methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl or octadecyl.

The condensation product, or'mixture of condensation products, wherein n represents the average number of such. groups present, are incorporated with the emulsion or dispersion of silver halide in a water-permeable macromolecular organic colloid in an amount from about 0.05 to about. 1.1 grams per molof silver halide.

The product resulting from the above reaction has a composition represented by the above structure. Hence, when the ethylene oxide is used in an amount sufiicient to introduce a certain weight of ethylene oxide, the resulting product'has a composition wherein n represents an average. value in the above structure.

The condensation products can be prepared in accordance with the exemplary procedure given below from aniline, a primary, secondary, tertiary or branched-chain alkyl bromide of l te 18 carbon atoms, e.g., methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl or octadecyl bromide and ethylene oxide. A mixture of two or more condensation products with different N-alkylanilines can be used if desired.

EXEMPLARY PROCEDURE Two molar parts of alkyl bromide, e.g., n-dodecyl-' I bromide, were treated with 1500 parts of aniline and the mixture was allowed to stand overnight. A,-deposit a 3 to 4 hours to carry the reactiouto completion (the especially at high temperatures and humidities. At-:-

tempts to reduce this fog by combining this class of nonoptical sensitizers with known antifogging agents have been tried but the use of such agents tends to reduce the beneficial speed increase contributed by the polyalkylene glycol sensitizer. This detrimental effect on speed is particularly noticeable when a photographic ele ment is exposed to low intensity radiation.

An object of this invention is to provide silver halide emulsions of improved sensitivity. Another object is to provide such emulsions which have enhanced radiation response, particularly to low intensity radiation. Yet another object is to provide such emulsions which have good contrast. A further object is to provide such emulsions by means of the use of economical and effective non-optical sensitizers. A still further object is to provide such emulsions by a simple and dependable proce-' dure. Still other objects will be apparent from the following description of the invention.

It has been discoveredsthat the above objects can be attained and, photographic silver halide emulsions of enhanced low-intensity response and contrast provided, in

accordance with the invention, by incorporating with a rose rapidly to about 100 C. and then gradually returned radiation-sensitive water-permeable colloid silverfhalide. I

emulsion sensitizing amounts of at least one condensation 1 product of an unsubstituted N-monoalkylaniline, with orwithout an alkyl substituent in the aromatic nucleus,

with ethylene oxide and containing at least three, or an.

average of at least three, oxyethylene groups. These condensation products can be represented by the general where X is hydrogen or alkyl of 1 to 18 carbon atoms, R is a normal or branched-chain alkyl radical. of 1 to 18 carbon atoms and n is a positive integer of 3 to 25 ethanol was placed in an appropriate vessel, one-half aniline hydrobromide, removed by filtration above, was

washed with acetone, the acetone evaporated, and the residue added to the main batch before the 3-4 hours sure'through a short column to remove the excess aniline; The distillation was carried out until the pot temperature reached'290 C. The pot residue was transferred to a vacuums'till and distilled to-purify the N-alkylaniline formed. The distillation was. carried out at a pressure of about 50 micronsto'yild80-95 of the theoretical quantity of the N-alkylaniline.

7 One molar part of the purified N alkylaniline and 2 ml. of boron trifluoride/diethyl ether complex were placed in ajflask whichwas flushedwith nitrogen gas. to remove all oxygen. Ethylene oxide gas was then 1 bubbledthrough the liquid at such a rate that good agi-.

tation was produced. The temperature o-f the mixture to room temperature. The contents of the flask were then heated to 140-150 C. while a gentlestream of nitrogen was passed through the flask to remove volatile substances, and after being cooled the product was transferredto a high vacuum still. This product was distilled at a pressure of about 50' microns to give a yield :of. -90% of the theoretical amount of the Z-(N-alkyl anilin'o)ethanol.

Q One molar part of the purified 2-(N-alkylanilino)- part of freshly cut sodium was added, the vessel was flushed with a stream of nitrogen gas and the contents were heated to 150 C. in a stream of nitrogen until all of-the sodium had dissolved. Ethylene oxidewas; then introduced until the weight gain indicated the ab.-'

'sorption of the desired quantity of ethylene oxide. The I product'of this reaction, depending uponthe alkyl halide. used in the preparation of the .alkylaniline, andtalso' depending on the amount of ethylene oxide allowed to condense withithe 2-(N;-.alkylanilino)ethanol, is the de- '7 red product of the above general formula.

The invention is not limited to any particular type of light-sensitive silver halide as it is useful with silver chloride, silver bromide, silver iodobromide, .silver chlorobromide, silveriodide, etc, emulsions and mixed emulsions of' these types. It is particularly efiicacious in silver iodobromide emulsions containing about 2 mole percent iodide and the rest bromide. These emulsions may be sensitized by means of the agents or adjuvants of the above structural formula and other sensitizers. Thus, noble .metal sensitizers, for instance gold com pounds, e;g., chlorauric acid and auric trichloride, may be present in association with :sulfur sensitizers, '.e.g., sodium sulfite, thiosinamine, allylthiourea, sodium thiosulfate, allyl thiocarbamate, alkali metal 'thiocyanates and sodium sulfide, these sensitizers to be usedin amounts up to 0.005% based on the weight of the silver halide. Moreover, the silver halide emulsions may contain one or more optical sensitizing agents, e.g., cyanine, carbocyanine, merocyanine, pseudocyanine, cyazine etc., dyes.

While gelatin is the preferred binding agent for the silver halide grains, other water-permeable amphoteric protein protective colloids, e.g., albumin and casein, can be used. Also, agar-agar, alginic acid and the alginates, polyglucuronic acid, polyvinyl alcohol, polyvinyl acetals including those containing color-forming nuclei, and other natural or synthetic water-permeable colloids useful in making photographic emulsions can be used as the original colloid during the precipitation, or in the final emulsion asjbulking agents.

The 'adjuvants of the above structural formula preferably are added to the silver halide emulsion after it has been brought to its maximum sensitivity and the conventional adjuvants are added just prior to coating onto a suitable support to form a photographic element. They'can, of course, be added at an earlier stage, that is, at the time of second digestion.

The invention will now be further illustrated by but is not intended to be limited to the following examples wherein the silver halide weight ratio, unless otherwise indicated, is 1.6 mole percent iodide and the remainder bromide. In these examples the emulsions were prepared and coated in the essential absence of actinic radiation, as is customary in the photographic art.

Example I C Hz C H: 11H

pheuyl-N The resulting emulsion was coated on a cellulose acetate 'film' support and exposed to X-rays in the presence of an intensifying screen at two different intensity levels. The exposure of greater intensity is designated as No. 2 and that of lower intensity as No. 1. The exposed elements were developed for five minutes 'in a developer of the following composition:

Grams N-rnethyl p-aminophenol hydrosulfate 3 Sodium sulfite (anhydrous) s.. 50

Hydroquinone 9 Potassium carbonate (anhydrous) 50 Potassium bromide 4.5

Water to make 1.0 liter.

and fixed, washed and dried in a conventional manner.

.The coatings were tested fresh, after room aging for one month and after one week at F. and 65% relative humidity. The results of tests for speed, gamma and fog are given below. Speed is given in terms of a reciprocal of exposure at a density of 0.7.

No. 2 Exposure No. 1 Exposure Fog Speed Gamma 'Speed Gamma Fresh:

Control 0. 26 800 2. 59 430 2. 30 Compound 0. 34 960 .3. 52 460 2. 71 One Month Room 0. 29 780 2.36 420 2. 06 l 0. 35 960 2. 63 430 2. 32 One Week 120 3,05%

REL:

Control 0-36 720 2. 06 460 2. 05 Compound 0.42 980 2. 38 500 2.13

Example 11 A silver iodobromide emulsion was made and tested as in Example 1 except that 0.31 g. per mole of silver halide of a condensation product predominating in a compound having the following formula:

CHnCHzO)1aH phenyl-N izHn was added to the emulsion.

The-results of the tests are as follows:

as in Example 1 except that 0.30 gram per mole of silver halide of a condensation product predominating in a compound having the formula:

was added to the emulsion as a final addition. The results of the tests are as follows:

No. 2 Exposure No. 1 Exposure Fog Speed Gamma Speed. Gamma Fresh: 7 v

.ControL'. 0.23 800 2. 50 430 2. 30 Compound 0. 24 080 3. 56 490 2. 77 0%? 1lIVeek 120 F., 65%

Control .0. as 720 2. 0a 460 2. 06 Compound 0.42 950 2.86 540 2. 06

Example IV A silver iodobromide emulsion was madeand tested asdescribed in Example Iexcept that 0.30 .g. per mole all.

. acetate film supports.

of silver halide of a condensation'product predominating in a compound having the formula:

crnoniomn phenyI- N CnHn was added to the emulsion as a final addition. The results of the tests are as follows:

A silver iodobromide emulsion of a fine grain cine negative type was made containing about 6.8 mole percent. iodide. The emulsion was digested with an organic sulfur compound and gold chloride. The emulsion was also optically sensitized with conventional carbocyanine dyes. To a portion of this emulsion there was added a final addition of 0.75 gramper mole of silver halide of a condensation product predominating in a compound having the formula:

CHrCH2O)4H phenyl-N This emulsion together with a control not containing the above compound were coated onto separate cellulose They were exposed in an Eastman negative IB sensitometer and developed for 7 minutes at 68 F. in a developer of the following composition:

' Grams N-methyl p-aminophenol hydrosulfate 0.80 Sodium sulfite (anhydrous) 90.00 Hydroquinone 1.0 Borax I 30 Potassium bromide 0.10

Water to make 1.00 liter and fixed, washed and dried in a conventional manner.

The coatings were tested fresh and after 10 days at 120 F. and 65% relative humidity. Rmults of tests for speed, gamma and fog are given below. Speed is expressed as a reciprocal ofexposure at a density of 0.2.

- Fresh Tests 10 days 120 F., v 65 RH.

Speed Gamma Fog 7 Speed 7 Fog Control 100 0.62 0.09 02 +0.08 A r'illino eompound 112 0.61 0.07 80 I 0.05

Example VI A silver iodobromide emulsion was made and tested as described in ExampleV except that 0.63 g. per mole of silver halide of condensation product predominatingin a compound having the formula:

cmomo'nH phenyl-N CHI I v was added to the test portion of the emulsion asa final addition. The results of the test are as follows'z -f' Fresh Tests 10 days 120 F.,

o R.H.

Speed Gamma Fog Speed Fog Control 100 0. 62 0. 09 62 0. 08 Aniline compound. 112 0. 68 0. 07 70 0. 06

Example VII A silver iodobromide emulsion was made, coated, and tested in the manner describedv in Example V except that to the test portion of the emulsion there was added 0.61 g. per mole of silver halide of a condensation product predominating in a compound having the formula:

CH2CH30 1IH phehyl-N The results of the tests are as follows:

Fresh Tests 10 days 120 F.,

Speed Gamma Fog Speed Fog Control 100 0. 62 0. 09 62 0. 0B Anlllno compound 112 0. 72 0. 07 0. 05

Example VIII 'A silver iodobromide emulsion Was made, coated, and tested as described in Example V except thatgto the test portion there was added 0.60 g. per mole of silver halide of a condensation product predominating in'a compound having the formula:-

CH2CH:0):5H

phenyl-N The results of the tests are as follows:

Fresh Tests 10 days 120 F.,

Speed Gamma Fog Speed Fog Control--. 0. 62 0.09 02 0. 08 Aniline eompound. 163 0.72 0.10 130 0.08

Example IX A silver iodobromide was made, coated and tested as described in Example V. except that 0.71 g. per mole of silver halide of a condensation product predominating in a compound having the formula:

I fcmcmonu phenyl-Ifl I i v p (301113 was added to the test portion of the emulsion. The results of the tests are as follows:

Fresh Tests 10 days F.,

Speed Gamma Fog Speed" Fog Control 100 0. 02 0.09 02 0.08 Anllino compound 3 112 0.66 0.07 70 p 0.07

. ExampleX A silver iodobromide emulsion was made, coated, and' tested as described in Example V except to the test pot tion of the emulsion there was .added 0.69 g. per mole. of silver halide of a compound having the formula:

A silver iodobromide emulsion was made, coated, and

tested as described in Example V except that to the test portion of the emulsion there was added (162g. per mole of silver halide of a compound having the formula:

CH2CH2 )12H phenylN CsHis The results of the tests are as follows:

Fresh Tests 10 days 120 F.,

65%RZH.

Speed Gamma Fog Speed Fog 5 Control 100 O. 62 O. 09 62 0. 08 Aniline compound 140 0. 72 0.07 70 0. 07

Example XII A silver iodobromide emulsion was made, coated, and tested in the manner described in Example V except that to the test portion of the emulsion there was added 0.60 g. per mole of silver halide of a compound having the formula:

CHrCHzOhaII phenyl-N OGHIB The results of the tests were as follows:

.Fresh Tests 10. days 120 1 Speed Gamma Fo Spend Fog Control '100 0. 62 0.09 I 62 10.08 Auilino compouncL. 163 '0. 72 '0. Q9 '70 0. 0?

Example XIII A silver iodobromide emulsion was made, coated, and tested in the manner described in Example V except that to the test portion of the emulsion there was added 0.67. g. per mole of silver halide of a condensation product predominating in a compound having the formula:

(CHaCHzOhsH .phenyl-N ExampleXIV A silver iodobromide emulsion :was made, coated, and tested as described inEXampIe V except that to the test portion ofthe emulsion there wasadded 0.65 g. per mole of silver halide of a compound having the formula:

The results of the tests-are as follows:

Fresh Tests 10 days 120 F., 65% RH. 1 1'5 Speed Gamma Fog Speed Fog Control 100 0.02 0.09 02' 0.08 v Aniline c0mpound 140 0.72 0.08 85 0.07

Example XV A silver iodobromide emulsion Was made, coated, and tcstedin the manner described in Example V except that to the test portion .of the emulsion there was added 0.62 g. permole of silver halide of a condensation product of a compound having the formula:

cHzcHs lzi v.phenyk-N The results of the tests are as follows:

7 Fresh Tests 10 days 120 F.,

Speed Gamma Fog Speed Fog Control 160 O. 62 O. 09 62 l). 08 40 Aniline compound. 140 o. 741 0. O8 90 0. it

In place of the alkyl groups shown on the nitrogen in the compounds of the examples, one may also have one of the following: ethyl, propyl, butyl, amyl, heptyl, octyl,

.nonyl, decyl, uudecyl, dodecy], tetradecyl, hexadecyl,

tridecyl, pentadecyl, etc.

The invention is not limited to light-sensitive silver iodobromide emulsions but may be used with simple and mixed silver chloride, silver bromide'and silver ,chloro- 5O bromide emulsions and mixtures of such emulsions. The aliphatic anilino polyoxyethylene compounds are usually added as one of the final additions justprior to coating but they maybe added at anytime after digestion. The emulsions may be coated on any suitable support to make the desired photographic element. Suitable supports include, in addition to the cellulose acetate set forth in the examples, other cellulose esters such as cellulose triacetate, cellulose acetate butyrate, cellulose nitrate, cellulose propionate; super polymers, e,g., nylon, polyethylene terephthalate, polyvinyl chloride, poly(vinyl chloride co vinyl acetate) and vinylidene chloride copolymers with vinyl acetate, acrylonitrilc, etc.; metal sheets, e.g., aluminum and zinc; and paper including resin-coated and.

baryta-coated paper; as well as glass plates. The sup- 65. ports, of course, may have various sublayers to improve adherence .to water-permeable organic colloids.

An advantage of the invention is that by the addition of :asingle compound there is obtained a high degree of non-optical sensitization without adversely affecting stability. A furtheradvantageis that novel adjuvants are relatively inexpensive and are readily available or can be easily prepared. I What'is claimed is:

1.:A' photographic silver halide dispersion a gelatin binding .agent, said dispersion containing in an amount like. A.

9 from about 0.05 to about 1.1 grams per mole of silver halide at least one compound of the formula (CHaCHzO) .H V

R p where X is a member taken from the class consisting of hydrogen and alkyl of 1 to 18 carbon atoms, R is an alkyl radical of 1 to 18 carbon atoms and n is a positive integer of at least 3.

2. A dispersion as defined in claim 1 wherein X is hydrogen, and n is 3 to 25.

3. A dispersion as defined in claim 1 wherein said silver halide is silver iodobromide containing about two mole percent iodide and the rest bromide.

4. A dispersion as defined in claim 1 which contains an organic sulfur sensitizing agent.

5. A dispersion as defined in claim 1 which contains an Organic sulfur sensitizing agent and a noble metal sensitizing agent.

6. A dispersion as defined in claim 1 wherein said silver halide is silver iodobromide.

7. A photographic element comprising a sheet suppor-t is a hydrophobiefilm.

X )CHaCHsW-H where X is a member taken from the class consisting of hydrogen and alkyl of 1 to 18 carbon atoms, R is an alkyl radical of 1 to 18 carbon atoms and n is a positive integer of at least 3.

8. An element as defined in claim 7 wherein said sup- References Cited in the file of this patent UNITED STATES PATENTS 2,161,322 Steindorfl et a1. June 6, 1939 2,271,622 Carroll et al. Feb. 3, 1942 2,423,549 Blake et al. July 8, 1947 2,708,162 Carroll et a1. May 10, 1955 2,757,089

Moessen July 31, 1956 

1. A PHOTOGRAPHIC SILVER HALIDE DISPERSION IN A GELATIN BINDING AGENT, SAID DISPERSION CONTAINING IN A AMOUNT FROM ABOUT 0.05 TO ABOUT 1.1 GRAMS PER MOLE OF SILVER HALIDE AT LEAST ONE COMPOUND OF THE FORMULA 